WASHINGTON (Reuters) - Diseases caused by worms and parasites are draining the health and energy of the poorest Americans, an expert said on Tuesday.


And diseases associated with the developing world, such as dengue fever and Chagas disease, may become a bigger problem for the United States as the climate changes, said Dr. Peter Hotez of George Washington University and the Sabin Vaccine Institute in Washington.

"The message is a little tough because they are not killer diseases -- they impact on child development, intellectual development, hearing and sometimes even heart disease," Hotez said in a telephone interview.

He said the diseases help to keep people mired in poverty, as infections may last years, decades or even lifetimes.

"Throughout the American South during the early twentieth century, malaria combined with hookworm infection and pellagra (a vitamin deficiency) to produce a generation of anemic, weak, and unproductive children and adults," Hotez wrote.

The parasitic diseases are having similar effects now, he said.

Hotez reviewed nine diseases affecting at least 10 million Americans for a report in the journal Public Library of Science Neglected Tropical Diseases, which he also edits.

"These diseases occur predominantly in people of color living in the Mississippi Delta and elsewhere in the American South, in disadvantaged urban areas, and in the U.S.-Mexico borderlands, as well as in certain immigrant populations and disadvantaged white populations living in Appalachia," he wrote.

They include ascariasis, the most common human worm infection. It is caused by a parasitic worm that lives in the intestine, and infected just under 4 million people in 1974 according to the last survey, in the South and Appalachia.

DOG DROPPINGS

Toxocariasis, a roundworm parasite transmitted in dog droppings, infected up 2.8 million poor black children living in inner cities, the South and Appalachia, Hotez said. The U.S. Centers for Disease Control and Prevention estimates these roundworms, which can cause intestinal illness and blindness, infect up to 14 percent of the U.S. population.

Strongyloidiasis is caused by a threadworm that lives throughout the body and infects 68,000 to 100,000 people. It may cause a hyper-immune reaction in some people.

Cysticercosis caused by the pork tapeworm and giardiasis, a diarrheal illness caused by a one-celled parasite, are also common, Hotez said.

One threat to babies is cytomegalovirus, which infects 27,002 newborn annually, causing deafness and mental retardation.

"It's amazing what we tolerate," Hotez said. He noted the United States spends $1 billion a year preparing for outbreaks of diseases that have not occurred, including smallpox, anthrax and avian influenza.

"But these (other) diseases are occurring among voiceless people," he said. "It's an unintended form of racism in a sense. We need to make these disease household words."

Chagas disease, caused by the parasite Trypanosoma cruzi, infects as many as 8 to 11 million people in Latin America and may become a U.S. threat, Hotez said. "In Louisiana, almost 30 percent of the armadillos and 38 percent of the opossums are infected with T. cruzi, and a case of Chagas disease was recently reported in post-Katrina New Orleans," he wrote.

"In the coming decade, global warming and increased flooding in the region could combine to promote dengue and Chagas disease epidemics among the poor in Louisiana."

Dengue, carried by mosquitoes, can sometimes cause a deadly hemorrhagic fever and has been reported in Texas.

(Reporting by Maggie Fox; Editing by Julie Steenhuysen and Doina Chiacu)